KR100212620B1 - Method of forming strip products from thermoplastic materials - Google Patents

Abstract

The extended trim strip product forming method comprises extruding a first strip of thermoplastic material from a die having an outlet having an area at least as large as the desired cross-sectional area of the strip product in a plane perpendicular to the extrusion direction. Immediately after the extrusion step, while the extruded strip is still plastic, it passes longitudinally between the co-molding rolls to shape the cross section of the extruded strip in the desired shape and cross section of the strip product. In addition, while passing between the rolls, a logo or lettering is molded on the strip. While the extruded strip passes between the co-molding rolls, the reinforcing strip as foil or thin metal is directed between the rolls in alignment with the extruded strip to bond the reinforcing strip to the extruded strip. In a second embodiment, one or more cables to a high strength flexible material, such as a metal wire, is bonded or embedded in the extruded strip during extrusion processing to move the extruded strip through the cooling bath without stretching or deforming the extruded strip. It functions as a tensioning mechanism. After cooling, the cable can be separated from the strip if desired.

Description

How to Mold Strip Products from Thermoplastics

1 is a side elevation view in diagram form illustrating a general sequence of processing steps of the present invention.

FIG. 2 is a cross sectional view of the extruded strip just before the forming roll (drawings are taken from line 2-2 of FIG. 1).

FIG. 3 is a cross-sectional view of the strip and the forming roll cut (drawing is taken from line 3-3 of FIG. 1).

3A is a plan view of a portion of a forming roll.

4 is a plan view of an exemplary strip product that can be shaped by the present invention.

4a is a cross-sectional view taken along the line 4a-4a of FIG.

4b is a view like 4a in another embodiment of the invention.

5 is a cross-sectional view of another embodiment of the present invention.

FIG. 6 is the same as FIG. 5 except for presenting the product after the final mechanical treatment step.

7 is a cross-sectional view of a strip of deformed form.

FIG. 8 is a view similar to FIG. 1 except for presenting a modified form of the present invention.

FIG. 9 is a cross sectional view taken along line 9-9 of FIG.

FIG. 10 is a cross sectional view taken along line 10-10 of FIG.

* Explanation of symbols for main parts of the drawings

10: screw type extrusion machine 12: first strip

16,18: forming roll 20: strip

22: Riley 24: roll the joint

30: Beth 32: belt type conveyor device

38: bottom surface 40, 42: side edge

44,46: projection 50: trim strip body portion

54: web 56: cable

70: Logo Part 76: Lettering

78: logo one

This application is filed on November 5, 1991, filed on November 5, 1991, the disclosure of which is hereby incorporated by reference in its entirety and incorporated herein by reference in US Pat. No. 5,171,499, entitled December 15, 1992. Partial continuation of Received Application No. 787,837, Part Continuing Application of Application No. 806,728, filed Dec. 12, 1991, now abandoned, Part Continuing Application of US Application No. 087,961, filed Jul. 6, 1993.

FIELD OF THE INVENTION The present invention relates to plastic forming techniques and more particularly to methods of forming strip shaped products from thermoplastics.

The present invention is particularly suitable for molding trim strips and decorative strip parts for automobile bodies and will be described in particular in this regard, however, as will be apparent, the present invention is applicable to a wider range of applications for various strip shaped products from thermoplastics. It can be used to mold.

Decorative and protective trim strips molded from thermoplastics are widely used in the automotive industry. The stream has been molded by both injection molding and extrusion processing. Both methods have certain disadvantages, which make them less ideal for mass, high speed production of the strip product. For example, when injection molding the strip product, the efficient production rate is closely related to the number of effective die cavities. Moreover, dies for these products are relatively inconvenient and expensive. In addition, the cycle times for these products tend to be relatively long because the strip products are flexible and difficult to remove and handle from the molding cavity without damage until they are markedly cool.

The extrusion of the strip product faces a different but difficult problem. Firstly, the use of extrusion methods is generally limited to products having a uniform cross section through the entire length. Secondly, it is difficult to handle the extruded product so that it is not deformed and unsuitable for use and transferred to the required cooling bath. In addition to the above, the final shape and contour of the extruded product is limited to what can be performed by a simple cutting operation.

The present invention overcomes the problems and disadvantages discussed above and provides a greatly improved method for producing strip-like products from thermoplastics. According to the invention, the method consists in extruding a first strip of thermoplastic material from a die having an outlet, which is the general shape of the desired strip in a plane perpendicular to the extrusion axis. Immediately after the extruding step, while the extruded strip is still plastic, the extruded strip is longitudinally passed between the co-molding rolls having an outer shape and contour to form the first extruded strip into its final desired shape and cross section. . In addition, a logo or lettering may be highlighted while the strip passes through the roller. In this case, the rollers include a carved logo or lettering. In addition, during the extrusion and forming step, a flexible cable of high strength material is bonded along the longitudinal edges of the extruded strip and used to apply transport force to the strip for subsequent processing such as cooling and the like.

By using a forming roll when the extruded strip is still warm and plastic, the extruded strip can be molded into its desired final shape, only by changing the surface shape of the forming roll to provide a longitudinal cross-sectional change of the strip. Do. In addition, the incidence by a carved roller provides a protruding or recessed logo or lettering. In addition, by coupling the flexible cable to the extruded strip, the extruded strip can be easily handled and pulled out through a subsequent cooling bath or the like.

Preferably and according to a more limited aspect, the flexible cable is connected to a strip extruded by a thin thermoplastic web with a flexible cable that can be easily separated after completion of cooling or other final processing steps.

According to an additional aspect of the present invention, the extruded strip can be cut to length simultaneously with its forming roll passing. That is, the forming rolls may have their surface contours such that the final shape of the strip product is shaped and cut to length. In addition, the final shape can be contoured in contrast to conventional extrusion products.

According to another aspect of the present invention, the present invention provides a method of forming an elongated trim strip having a predetermined cross sectional shape across its longitudinal axis. The method generally consists of extruding a first strip of hot melt thermoplastic material from a die having an outlet corresponding to a desired cross-sectional model desired. After the extrusion step, before the significant cooling of the extruded strip, the flexible metal cable is joined in length continuously along the longitudinal edge of the extruded strip. The extruded strip is then conveyed through the cooling bath with traction to the cable, and after passing through the cooling bath, the cable is separated from the strip.

According to another aspect of the present invention, the first strip can be molded by a co-extrusion method that provides multi-layer extrusion. This results in the resulting product having an outer surface of one shade and an inner body portion of a second tone. Alternatively, fired bodies having different physical properties can be combined to provide a final strip having different properties at the cross point therein.

In addition, according to the invention, the logo and / or lettering is molded completely in the trim strip.

As can be seen above, a first object of the present invention is to provide an improved method of forming an elongated thermoplastic strip member.

Yet another object of the present invention is the provision of a method that enables the high speed production of strip-shaped products from thermoplastics using conventional extrusion and roll forming techniques.

Another object is to provide a method of the type described which can be used to produce a multi-layer strip product having a cross sectional change along its length.

A further object is to provide a method of the type described which enables the formation of thermoplastic strip products without causing stress to the product or deforming the strip during processing.

These and other objects and advantages will be apparent from the following description when read in conjunction with the accompanying drawings.

With particular reference to FIGS. 1 to 4, the overall arrangement and processing sequence of the present invention can be most clearly understood. As illustrated in FIG. 1, the present invention generally relates to molding strip shaped products extending from any suitable thermoplastic material such as flexible polyvinyl chloride, thermoplastic olefins or thermoplastic urethanes.

Obviously, those skilled in the art will recognize other materials that may equally well be used as the description proceeds.

Specifically, Figure 1 presents a conventional screw-type extrusion machine 10, which ultimately produces a first strip 12 having a desired desired cross-sectional shape, which is the same general shape as the desired final cross-section of the strip to be produced. It is arranged. As will be evident later, the actual shape of the extruded strip can vary substantially from the final shape, but preferably the total cross-sectional area should be at least on the order of the maximum cross-sectional area of the final strip product.

After exiting the extruder, the strips are suitably supported by a roll conveyor or table and fed directly to a pair of opposite forming rolls 16 and 18, with the rolls of which their axis of rotation extends perpendicular to the direction of movement of the strip element. It is installed if possible.

The forming rolls 16 and 18 can be driven in a synchronous relationship, freely actuated or driven independently, and have a cavity outer surface model arranged to mold the strip product to its desired final cross-sectional model. As can be appreciated, the rolls are paired with surface contours to form the first extruded strip into the desired final cross-sectional model that can vary longitudinally along the strip product. For example, as illustrated in FIG. 4, the strip may vary from one end of a relatively large area to the latter end of a rather narrow shape. The cross section of the strip may be as illustrated in FIG. 3, for example.

Simultaneously with the forming rolls 16 and 18 of the extruded strip, a thin strip of metal reinforcement material 20 is supplied to a position between one side of the extruded strip and the corresponding roll 16 or 18. As shown in FIG. 1, a thin aluminum strip 20 of about 0.254 to 0.508 mm (0.010 to 0.020 inch) thick is underneath the strip extruded from the rail 22 through the cavity roll 24 and the forming roll 16. Is supplied on top. The strip 20 is arranged side by side with the extruded strip and bonded thereto while passing between the forming rolls 16 and 18. Of course, the actual bonding of the strip 20 to the extruded strip 12 can be improved using various surface treatments on the strip if desired or necessary.

The reinforcing strip 20 acts to reinforce the resulting strip product and acts as an attachment means for connecting the resulting product to automobile panels or the like that are connected in many product types. As shown in FIG. 1, the reinforcement strip 20 provides a means for conveying the molded strip product to a subsequent cooling bath 30. As indicated above, the bath 30 is simply a water bath through which the strip product is conveyed from the forming rolls 16 and 18 by a suitable belted conveyor device 32. It should be understood that any of a variety of types of transport or traction mechanisms can be used to engage the metal reinforcement strip 20 and to advance the molded product to or through any of the various cooling devices.

2 and 3 generally illustrate cross-sections of extrusion strips and the resulting product of the exemplary type. In FIG. 2, the extruded strip is shown to have a somewhat convex top surface and generally a flat bottom surface 38. Lateral edges 40 and 42 are rounded and downwardly extending bead shaped protrusions 44 and 46 extend along edges 40 and 42, respectively. This provides a general arrangement for the receipt of the metal strip 20, and as shown in FIG. 3, the strip can be sized to fit within the flat space between the beads 44 and 46. The presentation of FIG. 4 illustrates the cross-sectional area and shape of the forming roll in the position where the cross section of FIG. 3 is formed. As illustrated above, the cross-section of FIG. 2 passes through the shape of the forming roll and is shaped to the desired final cross section, and the beads 44 and 46 roll to a point extending below the bottom surface of the aluminum reinforcing strip 20. It is further molded by (16). The shape can then be mechanically cut to remove the beads to a level corresponding to the surface level of the reinforcing strip 20. In many cases, mechanical cutting of the forming surface of the strip allows for better matching of the surface to which the strip is attached and provides a sharp and sophisticated outer edge corner that may not always be obtained during roll forming operations.

As can be seen in FIGS. 3-4 (b), a logo or lettering can be highlighted on the strip. As illustrated in FIGS. 3 and 3 (a), the roller 18 includes a carved logo portion 70. Logo portion 70 may be engraved to protrude 72, dent 74, or both on a strip to provide the particular logo desired. In the logo illustrated in Figure 4 (a), the lettering 76 is etched in and the surrounding circle 78 is protruding. Also, as shown in Figure 4 (b), the logo circle 78 is recessed and the letter 76 is protruding. Any combination of protruding or dents can be used to provide the desired logo or lettering with the desired shape or type.

The logo portion 70 is located on the roller 18 so that the logo is molded in the desired position on the trim strip. Thus, the logo can be shaped during the rolling process when the strip is soft and heated. In addition, a second set of forming rollers may be used to mold the logo and / or lettering on the strip.

5 shows an alternative form for the product that can be produced by the method. In Figure 5, the main body of the strip is molded from the first thermoplastic material designated by the number 50. Through conventional co-extrusion techniques, the surface layer 52 of another thermoplastic material can be extruded simultaneously on the core strip 50 before the extruded strip passes through the forming rolls 16, 18. The molded strip with aluminum reinforcement 20 is subsequently mechanically cut or shaped to remove tab portions 50a and 50b to remove the tab portions 50a and 50b, which are smooth and planar as illustrated in FIG. 6 and discussed generally with reference to the product of FIG. It can provide the rear.

As shown in FIG. 5, the strip product shaped by the present invention can be cut to length by forming rolls 16 and 18 with contour ends. Only by proper shaping of the forming roll can the cut portion be inserted into the roll so that the product is cut into separate lengths and shapes during the rotation of the roll. In addition, logos and / or lettering may be added to the strip of FIG. 5 as described above.

Figure 7 shows the strip in a modified form possible in the present invention. In this form, the two reinforcing strips 20a are joined to the back side between the shaped bead-like portions 54. Alternatively, perforated reinforcing strips may also be used.

Under certain conditions and for certain applications, the reinforcing strip may be in the form of a thin film of metal or other material that can withstand the temperature of the extrusion. In any case, the materials chosen for the reinforcing strips are chemically compatible with the protrusions, provide the strength needed to pull the extruded strips through the cooling bath, and provide physical properties to allow the continuous handling, installation and use of thin strips. Should have

8-10 illustrate additional embodiments of the invention in which thin flexible cable members are incorporated into the extruded strip to provide an apparatus for transporting the strip during various process steps without deforming or stretching the extruded strip. In the embodiments of FIGS. 8-10, like reference numerals have been used to identify the same or similar terms corresponding to those of the embodiments of FIGS. 1-7. In such embodiments of FIGS. 8-10, these numbers are differentiated by the addition of prime suffixes. In the embodiment of FIGS. 8-10, the extruded strip 12 ′ passes between forming rolls 16 ′ and 18 ′, which serves to reduce the extruded cross section to its final desired shape. As can be appreciated from the preceding discussion with reference to the embodiments of FIGS. 1-7, the actual extruded shape may have various specific shapes. In the embodiments of FIGS. 8-10, the exemplary shape is shown in FIG. 9 and at least ultimately the main body portion sized and shaped so that the overall size and shape generally corresponds to the final desired cross section of the desired final trim strip. And 50. In addition, a logo or lettering portion may be added to the roller 18 'to highlight the strip as described in FIG. A rather small portion 52, which is preferably connected to the body portion 50 by a relatively thin web 54, is associated with and connected to the main body portion 50.

The extruded strip form shown in FIG. 9 can be shaped as discussed above with reference to the embodiments of FIGS. 1-7 in order to reduce it to the desired final shape. That is, they can be shaped to shape the body of the trim strip with individual precut lengths having the desired end shape in the form shown in FIG. Alternatively, the forming rolls may be molded to form only continuous trim strips without preformed ends. In any case, when strip 12 'passes between rolls 16' and 18 ', a relatively small diameter, high strength flexible cable 56 is fed from reel 58 to a position between rolls 16' and 18 '. . As illustrated in FIG. 10, the cable 56 enters into the roll at a position connected with the extruded portion 52. The rolls 16 and 18 make the body portion 50 into its desired final shape, and the web 54 is somewhat tapered when the cable 56 is embedded into the portion 52.

As will be apparent from the above, the cables 56 are continuously connected along the side edges of the main body of the shaped trim strip 12 ′. That is, the web 54 acts to connect the cable to the body of the trim strip, thereby moving the trim strip by applying a tension force to the cable 56. In this way, the force used to move the trim strip through the cooling and continuous process steps need not be applied along the length of the strip. Rather, they are applied evenly from the cable through the thin web portion to move the strip without placing it under longitudinal tension.

After completion of the cooling and continuous process steps, the web 54 may be cut to remove the cable 56 and the extruded portion 52 from the terminated trim strip body portion 50.

It is contemplated that the cable 56 may be applied to the trim strip extruded in various ways other than direct rolling in the manner described in FIG. For example, if desired, the cable 56 may be passed directly into the extrusion head and die to appear simultaneously with the extrudate. That is, the cable will be in place as the material from the extrusion die. In this case, their final cross section versus continuous length of the trim strip can be extruded directly from the dispensed forming roll stage and the extruder. However, in this situation, the individual molded end lengths of the trim strips cannot be molded. In addition, the cables can be used with the flat permanent reinforcement strips discussed in the embodiments of FIGS. In any case, the use of a cable facilitates the processing and additional handling of the trim strip and can be easily removed because it is connected to the extruded body by a relatively thin web.

As can be appreciated, an alternative location for cable 56 may be provided. In addition, multiple cables can be used with a single trim strip, or a single cable can be used between the bodies of two separate main trim strips.

The present invention has been described in sufficient detail to enable one of ordinary skill in the art to make and use the same. Apparently, modifications and variations may occur to those skilled in the art upon reading and understanding the specification. All such modifications and variations are intended to be included herein when included in the appended claims or their equivalents.

Claims (15)

Extruding the first strip of thermoplastic from a die having an outlet having an area greater than or equal to the desired cross-sectional area of the strip in a plane perpendicular to the extrusion direction; Immediately after the extruding step, while the extruded strip is still plastic, the extruded strip is passed longitudinally between the co-molding rolls to form the cross-sectional shape of the extruded strip into the desired shape and cross section; Shaping protruding or dents on the strip before significant cooling; While the strip is extruded and its cross section is molded, a flexible cable is joined in length along the edge of the strip such that it extends to the length of the strip in a continuous engagement with the strip; Continuously moving the extruded and shaped strip through a cooling bath using a flexible cable. The method of claim 1 wherein the flexible cable is cut from the extruded and shaped strip after completion of the cooling step. The method of claim 1, wherein the flexible cable is joined to the extruded strip by a thin web of thermoplastic material extruded simultaneously with the strip along the edge of the strip. The method of claim 1, wherein the flexible cable is joined to the extruded strip prior to passing the strip through the co-molding roll. The method of claim 1 wherein the flexible cable is coupled to the extruded strip while the extruded strip passes through the co-molding roll. 4. The method of claim 3, wherein the cable is joined along the longitudinal edge of the strip by a thermoplastic thin web that is cut from the strip after completion of the passage through the cooling bath. 7. The method of claim 6 comprising directing the cable in a mated relationship with the strip concurrently with the extrusion step. The method of claim 1 wherein the marking is molded while passing through the forming roll. Extruding a first strip of hot melt thermoplastic material from a die having an outlet corresponding to the desired predetermined cross-sectional shape; After the extruding step, before the significant cooling of the extruded strip, continuously join the flexible metal cable to length along the length edge of the extruded strip; Forming marks on the strip before significant cooling; Traction is applied to the cable to carry the extruded strip through the cooling bath; After the passage of the extruded strip through the cooling bath, cutting the cable from the strip, the method of forming a trim strip extending a predetermined transverse cross-sectional shape of the longitudinal axis of the strip. The method of claim 9 comprising extruding a thin continuous web of material along the longitudinal edges of the strip and using the extruded web to bond the cable to the strip. 10. The method of claim 9 comprising shaping the extruded strip into a final desired shape by applying a forming roll thereto prior to transporting the extruded strip through the cooling bath. The method of claim 11, wherein the cable is extruded into a thin continuous web. 10. The method of claim 9, wherein the marking is molded while passing through the forming roll. The method of claim 9, wherein the indication is a logo. The method of claim 9, wherein the indication is lettering.